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Identifying the relative loads (%1RM) that maximize power output (Pmax-load) in resistance exercises can help design interventions to optimize muscle power in older adults. Moreover, examining the maximal mean power (MPmax) and peak power (PPmax) values (Watts) would allow an understanding of their differences and associations with functionality markers in older adults. Therefore, this research aimed to 1) analyze the load-mean and peak power relationships in the leg press and chest press in older adults, 2) examine the differences between mean Pmax-load (MPmax-load) and peak Pmax-load (PPmax-load) within resistance exercises, 3) identify the differences between resistance exercises in MPmax-load and PPmax-load, and 4) explore the associations between MPmax and PPmax in the leg press and chest press with functional capacity indicators. Thirty-two older adults (79.3 ± 7.3 years) performed the following tests: medicine ball throw (MBT), five-repetition sit-to-stand (STS), 10-m walking (10 W), and a progressive loading test in the leg press and chest press. Quadratic regressions analyzed 1) the load-mean and peak power relationships and identified the MPmax-load, MPmax, PPmax-load, and PPmax in both exercises, 2) the associations between MPmax and PPmax in the chest press with MBT, and 3) the associations between MPmax and PPmax in the leg press with STSpower and 10Wvelocity. In the leg press, the MPmax-load was ∼66% 1RM, and the PPmax-load was ∼62% 1RM, both for women and men (p > 0.05). In the chest press, the MPmax-load was ∼62% 1RM, and the PPmax-load was ∼56% 1RM, both for women and men (p > 0.05). There were differences between MPmax-load and PPmax-load within exercises (p < 0.01) and differences between exercises in MPmax-load and PPmax-load (p < 0.01). The MPmax and PPmax in the chest press explained ∼48% and ∼52% of the MBT-1 kg and MBT-3 kg variance, respectively. In the leg press, the MPmax and PPmax explained ∼59% of STSpower variance; however, both variables could not explain the 10Wvelocity performance (r2 ∼ 0.02). This study shows that the Pmax-load is similar between sexes, is resistance exercise-specific, and varies within exercises depending on the mechanical power variable used in older adults. Furthermore, this research demonstrates the influence of the MBT as an upper-limb power marker in older adults.

Objective: Motivation seems to be a fundamental indicator of long-term physical exercise adherence. Self-Determination Theory (SDT) argues that social environment plays a central role in the satisfaction of basic psychological needs, which might directly affect the quality of one's motivation. Individuals who appear to be more self-determined tend to persist longer at certain behaviors. Therefore, this body of work intends to analyze the relationship between motivational variables and behavioral outcomes in the exercise context, having as theoretical background the Self-Determination Theory.Methods: This systematic review was conducted through an electronic search on Web of Science, PubMed, SPORTDiscus, and PsycINFO. Data such as instruments, main predictors and results were collected from studies published between 1985 and 2018. A total of 35 empirical studies were considered for a detailed analysis.Results: Results showed the relevance of autonomy support performed by exercise professionals, as well as the major contribution that these behaviors have toward the satisfaction of basic psychological needs, besides the inherent benefits of developing more autonomous regulations. According to the literature, few studies have analyzed interpersonal thwarting behavior and the way this relates to basic psychological needs' frustration. Nether less, there seems to be a negative relationship between less self-determined regulations and exercise practice.Conclusion: Despite the existence of numerous cross-sectional studies that demonstrate positive correlations between SDT and behavioral outcomes in the exercise context, longitudinal research that analyzes all six dimensions of interpersonal behaviors and their relationship with persistence and adherence to exercise proves to be crucial. However, according to this review, interventions based on SDT appear to be fundamental when it comes to promote the maintenance of a long-term exercise practice.